
Engine Control Module/Powertrain Control Module (ECM/PCM)
('95 - 00 Models except Dl6Y5 engine with M/T)
NOTE:. When there is no Diagnostic Trouble Code lDTC) stored, the MIL will staY on if the SCS
seruice connector is connected and the ignition switch is on.. lf this symptom is intermittent, check for:- A loose No. 25 (METER) {7.5 A) fuse in the underdash fuse/relay box- A loose Fl E/M (15 Alluse in the undeFhood fuse/relay box- A loose No. 13 FUEL PUMPfuse (15 A) in the under-dash fuse/relay box- An intermittent shon in the wire between the ECM/PCM (A18) and the gauge assem'
- an intermittent short in the wire between the ECM/PCM (C19) and the MAP sensor- An intermittent short in the wire between the ECM/PCM {C28), the TP sensor, the
EGR valve lift sensor (D16Y5 engine) and/or the Fuel tank pressure sensor ('96 D16Y8
engine (coupe),'97 D16Y7 engine lcoupe: KL model, sodan: KL (LX) model)"g7
Dt6Y8 engine (coupe: all mod;ls, sedanl KL model),'98-all models,'99-al' models''00-all models.- PGM'FI main relay. See the oBD ll scan tool or Honda PGM Tester user's manuals for specific operating
instructrons,
ECM,/PCM CONNECTOR A I32PI
Wire side of {emale terminals
The Mrlfunction Indicator LamP{MlL) never comes on {even tor
two seconds) after ignition is
turned ON lll).
Turn the ignition switch ON lll).
- Repair shott or open in thowire bstwoon No. 25 IMETER)l?.5 A)tuse and gauga tsom_blv.- Reolace No. 25 (METERI (7.5
Alluse.
ls the low oil pressure light on?
Try to start the engine.
Check for an opon in the wire orbulb (MlL line):1. Turn the ignition switch OFF.2. Connect the ECM/PCM con'
nector terminal A18 to bodyground with a iumper wire.
3. Turn the ignition switch ON (ll)
Does the engine start?
- Repair open in tho wire3
betwoon ECM/PCM (A18) andgaugo .*tembly.- Rool.ce the MIL bulb.
Substitute a known-good ECM/
PCM and rochoc&. lf sYmptom/indication goes sw6y, repl.ce
tho original ECM/PCM.Turn the ignition switch OFF.Inspect Fl E/M (15 A)fuse in theunderhood Iuse/relay box.
Rop.ir short in the wirc
betwo€n Fl E/M (15 A) luso
and PGM-Fl mrin rGl.y.Reol.ce Fl E/M (15 A)tusa.
lnspect No. 13 FUEL PUMP {15 A}
luse in the under-dash fuse/relay
- Reoair short in the wiro
between No. 13 FUEL PUMP
115 Al luse sod PGM-FI mainrelay.- Reolace No. 13 FUEL PUMP115 A) tuse.
(To page 11 112)
(cont'd)
11-111
.f,

PGM-FI System
(From page'11-111)
Check loi an open in the wires(lGP linesl:1. Disconnect the lueliniector andIAC valve connectors.2. Turn the ignition switch ON (ll).
3, Measu re voltage betweenbody ground and ECM/PCMconnector terminals 81 andBg individually.
- Repair open in the wiro(3)between ECM/PCM lBl, B9land PGM-Fl main relay.- Check tor poor connectionsor loose wires al the PGM-FImain relav.- Test tho PGM-FI main rehy(3.e page 11-237).
ls there battery voltage?
Check tor an open in the wires(PG, LG lines):1. Reconnect the fuel iniectorand IAC valve connectors.2. Measure voltage betweenbody ground and ECM/PCMconnector terminals 82, 810,820 and 822 individually.
Repair open in the wirels)between ECM/PCM and G 101llocated ai the l6ft side of thointaks m.nifoldl thrt h.d morethan 1.0 V.
ls there lessthan 1.0 V?
Check for a short in the wires
{VCCI, VCC2 lin6s}:Measure voltage between bodyground and ECM/PCM connectorterminals C19 and C28 individually.Check toa a 3hort in s 3ensor:While measuring voltagebetween body ground and ECM/PC[/t connector terminals C19and C28 individually, disconnectthe 3P connector of each sensorone at time:. MAP sensor. TP sensor. EGR valve. Fueltank pressure sensor
ls there approx.5 V?
Reoair short in lhe wire betwe.enMAP 3ansor, TP sensor, EGRvalve, Fuel tank pres3ure 3ensorand ECM/PCM {Cl9, C28).
ls there approx. 5 V?
Substiiute a known-good ECM/PCM and racheck. ll symptom/indicetion goes eway, replaceth6 original ECM/PCM.Replace tho sansor that had.pprox. 5 V.
Engine Control Module/Powertrain
('99 - 00 Model except Dl6Y5 (M/Tl
Module (ECM/PCM)
(cont'd)
Control
engine)
ECM/PCM CONNECTOR B {25P)
LG1 (BRN/BLKI
Wire side of female terminals
ECM/PCM CONNECTOR C (31P)
female terminalsvcc2IYEL/BLUIvccl{YEL/RED)
Wire side of female terminals
11-112

PGM-FI System
Fuel Supply System
D017-il Th""""ntool indicates Diagnostic Troubte Code {DTC) p0171;Thefuet system istoo lean.
1P0172 | fne scan tool indicates Dlagnostic Trouble Code (DTC) P0172:Thefuel system istoo rich.
Description
By monitoring the Long Term Fuel Trim, long term malfunctions in the fuel system will be detected.lf a malfunction has been detected during two consecutive trips, the MIL will come on and DTC P0171 and/or P0172 will bestored.
NOTE: lf some of the DTCS listed below are stored at the same time as DTC P0171 andlot P0172, ltouhleshoot those DTCSfirst. then recheck for DTC P0l7l andlot P0172.
P0106-8, P1128*3. *5, P1129*3 *5 MAP Sensor
P0135; Primary HO2S Heater
P0137. P0138: Secondary HO2S
P0'141: Secondary HO2S Heater
P0401: EGR Flow Insufficient*1
P0441: EVAP System Insufficient Purge Flow*6
P1259: VTEC System*,
P1491:EGR Valve Lift Insufficient*r
P1498: EGR Valve Lift Sensor Hjgh Voltage*r
*r: D16Y5 engines*' : Dl6Y5, D16Y8, 81642 engine*3: '97 models*a:'96 modelsf 5: '98 - 00 models*6: '96 D16Y5 engine,'96 D16Y7 engine,'96 D16Y8 engine (sedan),'97 D16y5 engine,,97 D16y7 engine (coupe: KA, KC mo+els, sedan KA. KC, KL (DX) models. hatchback; all models),'97 D16Y8 engine (sedan: KA, KC models)
Possible Cause
DTC P0'171
loo lean
DTC P0172
too rach
Fuel Pump insuff icient f lovpressure
Fuel Feed Line clogged, leaking
Fuel Pressure Regulator stuck open
Fuel Filter clogged
Fuel Injector clogged, air inclusion
Gasoline doesn't meet Owner's Manual spec.
Primary HO2S (Sensor 1) deteriorated
MAP Sensor range/performance*.
EGR System malfunction (too much flow)*1
Valve Clearance
Exhaust leak
Fuel Pressure Regulator clogged, stuck closed
Fuel Return Pipe clogged
Fuel Injector leaking
Gasoline doesn't meet Owner's Manual spec.Primary HO2S (Sensor 1) deteriorated
MAP Sensor range/performance*a
EGR System insufficient flow*1
EVAP Purge Control Solenoid Valve leaking, stuck opened
Valve Clearance
11-164

t
Troubleshooting Flowchart
'l
NO
a-,-:- -
YES
- The MIL ha3 b€on rePorled on.- DTC P0171 a^dlot P0172 arc
stored,
is the fuel pressure OK?
Check the fuel pt€ssure regulator
and fusl re{urn pipe.ls the fuel pressure too high
ortoo low?
Check the Primary HO2S:
1. Start the engine. Hold the
engine at 3,000 rpm with no
Ioad (in Park or neutral) until
the radiator Ian comes on
2. Check the Primary HO2S(Sensor 1) output with the
scan tool,
Check the tu6l pump. fuel leedpipe, fu€l fiher, and Iuel Pressureregulator.
Does it stay at less than 0.3 V
or more than 0.6 V?
Check lor a sticking or leaking
EVAP purge control solenoid
With a vacuum PumP, aPPIY vacu-
um to the EVAP purge control
solenoid valve from the intake
manifold side.
Does it hold vacuum?
Check the MAP sensor outputr
1. Turn the ignition switch ON (ll)
2. Check the MAP with the scan
tool.
Check th6 response of the MAP
sensoa:1. Start the engine.2. Check the MAP with the scan
tool.
ls a MAP of 40.0 kPa 1300 mmHg,12.0 inHg) or less indicated within
one second after starting the
engine?
- Check th€ valve cloarance.- Check the EGR rystem lD16Y5enginel.- lf they are OK, r€place the tueliniocto]3.
1 1-165

PGM-FI System
Random Misfire
lFoioo l*u o, [FTioo l*' *' and
The scan tool indicates Diagnostic Trouble Code (DTC)
P0300*5 or P1300*3 *1 and some of P0301 - P0304:Random misfire.Description
Misfire detection is accomplished by monitoring the crankshaft speed with the crankshaft speed fluctuation (CKF) sensorwhich is attached to the crankshaft.
lf misfiring strong enough to damage the catalyst is detected. the MIL will blink during the time of its occurrence, and DTCP0300*5 or P1300*3'*' and some of DTCs P0301 through P0304 will be stored. Then, after misfire has ceased, the MIL willcome on.
lf misfiring that increases emissions is detected during two consecutive driving cycles, the MIL will come on, and DTCP0300*5 or P1300*3 *a and some of DTCS P0301 through P0304 will be stored.NOTE: lf some of the DTCS listed below are stored at the same time as a misfire DTC. troubleshoot those DTCS first, thenrecheck for the misfire DTC.
P0106*4. P0107. P0108, P1128*3 *5, Pl129*3 *5; MAP sensorP0131. P0132: HO2S
P0171, P0112i Fuel metering
P0401, P 1491, P1498: EGR svstem*1P0505: ldle Control SystemP1253: VTEC System*,P1361, P1362: TDC sensorP1381, Pl382: CYP sensorP1508: IAC valve
Possible Cause. Fuel pump insufficient fuel pressure, amount of flow. Fuel line clogging, blockage, leakage. Fuel filter clogging. Fuel pressure regulator stuck open. EGR system malfunction*1. Distributormalfunction. lgnition coil wire open. leakage *l: D16Y5 engine. lgnition control module malfunction *2: D16Y5, D16Y8, Bt6A2 engine. MAP sensor range/performance, poor response*r *3: '97 models. Valves carbon deposit *4;'96 models. Compression low *5: '98 - 00 models. IAC valve malfunctionr.. VTEC system malfunction*,. Fuel does not meet Owner's Manual spec., lackoffuel. HO2S. HO2S circuit
Troubleshooting
By test-driving, determine the conditions during which misfire occurs, Depending on these conditions, test in the orderdescribed in the table below.
Possible
- --^ ---
rage
causeEGR*1
system
Crankshaft
position (CKP)
sensor
Fuel
pressure
Distributor and
lgnition wirestcMClearance
tAc
ValveMAP
sensor
section 611-230,
231section 23section 23section 611-19411
Only low rpm and
loado@@oo
Only accelerating@o@@
Only high rpm and
toaooo@
Not specificoo@
NOTE: lf misfire doesn't recur, some possible causes are fuel that doesn't meet owne/s manualspec, lack of fuel, carbon deposits on spark plug, etc.
1 1-1 66
I
P0304

I
Misfire Detected in One Cylinder
P0301 | The scan tool indicates Diagnostic Trouble Code (DTC) P0301: Cylinder 1 misfire detected.
[F03O2l 16"""untool indicates Diagnostic Trouble code (DTc) P0302: Cylinder2 misfire detected.
[FO3Ofl 16" ".un toot indicates Diagnostic Troubte Code (DTC) P0303; Cylinder 3 misfire detected.
I P0304 I ths..rr tool indicates Diagnostic Trouble Code (DTC) PO3O4: Cylinder 4 misfire detected.
D€scription
lMisfire detection is accomplished by monitoring the crankshaft speed with the crankshaft speed fluctuation (CKF) sensor
which is attached to the crankshaft,
lf misfiring strong enough to damage the catalyst is detected, the MIL will blink during the time of its occurrence, and DTC
PO3O1, P0302, PO3O3 or P0304 will be stored. Then, after the misfire has ceased, the MIL will come on.
lf misfiring that increases emissions is detected during two consecutive driving cyclss, the MIL will come on, and DTC
P0301, P0302, P0303 or P0304 will be stored.
NOTE: lf some of the DTCS listed below are stored at the same time as a misfire DTC, troubleshoot those DTCS first, then
recheck for the misfire DTC.
PO106*1, P0107, P0108. P1128*3'*5, P1129*3'*5: MAP sensor
P0131, P0132: HO2S
P0171, P0172iFuel suppiy system
P0335, P0336: CKF sensor
P0401. P1491, P1498: EGR system
P0441: EVAP system Insufficient purge flow*6
Pl359. P1361. Pl362: TDC sensor
P1381. Pl382: CYP sensor*o: '96 models*6: '96 D16Y5 engine,'96 D16Y/ engine,'96 D16Y8 engine {sedan),'97 D16Y5 engine,'97 D16\4, engine (coupe: KA,
KC models, sedan KA. KC, KL (DX) models, hatchback:all models),'97 D16Y8 engine (sedan: KA, KC models)
Possible Cause
. Fuel injector clogging, fuel leakage, air leakage
. Fuel injector circuit open or shorted
. Spark plug carbon deposits, fouling, malfunction
. lgnition wires open. leaking
. Distributor malfunction
. ComDression low
. Valve clearance out of spec
. VTEC system malfunction (D16Y5, D16Y8. 81642 engine)
. HO2S
. HO2S circuit
(cont'd)
11-167
r'a

Emission Gontrol System
System Description
The emission control system includes a Three Way Cata-lytic Convener (TWC), Exhaust Gas Recirculation (EGR)
system,. Positive Crankcase Ventilation (pCV) system andEvaporative Emission (EVAP) Control system. The emis-sion control system is designed to meet federal and stateemission standards.*: D16Y5 engine
Tailpipe Emission
Inspestion
@@ Do not smoke during ihis procedure. Keepany open flame away from your work area.
1. Start the engine. Hold the engine at 3,000 rpm withno load (in Park or neutral) until the radiator fancomes on. then let it idle.
2. Connect a tachometer.
Check and, if necessary, adjust the idle speed (see
page 11-220 - 223).
Warm up and calibrate the CO meter according to themeter manufacturer's instructions.
Check idle CO with the headlights, heater blower,rear window defogger, cooling fan, and air condition-er off.
NOTE: (Canada) Pull the parking brake lever up.Start the engine, then check that the headlights areoff.
CO mete. should indicate 0.1% maximum.
NOTE: '98 Dl6Y5 engine - lf the idle speed incress-es to 8101 50 rpm, this means the EVAp system ispurging the canister. To stop the purging temporari-ly. raise the engine speed above 1,000 rpm with theaccelerator pedal, then slowly release the pedal.
11-252
eFORWARD -
Three Way Catalytic Converter
(TWCI
Doscription
The Three Way Catalytic Converter (TWC) is used toconven hydrocarbons (HC), carbon monoxide (CO), andoxides of nitrogen (NOx) in the exhaust gas to carbondioxide (COr), dinitrogen (N,) and water vapor.
D15Y5, D16
, engine:
'99 - 00 D16Y8, 81642 engine:
ENGINE SIDE
t

Emission Control System
Exhaust Gas Recirculation (EGR) System (D16yS engine)
Doscription
The EGR system is designed to reduce oxides of nitrogen emissions (NOx) by recirculating exhaust gas through the EGRvalve and the intake manifold into the combustion chambers. lt is composed of the EGR valve. EGR vacuum conrrot vatve.EGR control solenoid valve. ECM and various sensors.The EcM contains memories for ideal EGR valve lifts for varying operating conditions, The EGR valve lift sensor detectsthe amount of EGR valve lift and sends the information to the ECM. The ECM then compares it with the ideat EGR valve liftwhich is determined by signals sent from the other sensors. lf there is any difference between the two. the EcM cuts cur-rent to the EGR control solenoid valve to reduce vacuum applied to the EGR valve.
EGR CONTROLCVT: SOLENoID vALvE
EGN VALVE LIFT SENSOR
BLK
I
I
11-254